Bucking, hesitation at half throttle

84turbo6

Member
Alright guys it's not a buick, it's for my 99 camaro ls1. Since ls1tech has become impossible to post on I'm going to ask the guys that always helped me on here. Soo it rained very hard a few months ago and my car got submerged in water, enough to touch the alternator but not enough to flood the car, it was sitting I was not driving it. Got home from work me and my friend pushed the car to a different spot since it was sitting curb side, after that the car hesitates at almost exactly 2500 rpm in every gear above 1st. I have tried almost everything, I changed o2 sensors I pulled spark plugs cleaned them, i changed alternator and battery, I switched around coil packs I checked for air and exhaust leaks, checked fuses checked fuel pressure through rail, changed fuel filter, unplugged every connection point and reconnected, still hesitates, when I get past the 2500 rpm point car runs fine then WOT it will die at about 5000rpm but will start right back up as if nothing happened. Car never did this before that heavy rain, I did not try to start it while the water was high i wanted till it stopped raining and it started right up just with the hesitation now? I am baffled
 

AntMan

Member
If the water level reached as high to your alternator, then your ECM (if mounted under hood can not recall location) my be the culprit. Had similar issues with a bad ECM.
 

84turbo6

Member
That's funny I had to change the ecm in the 84 GN because water got in the window, you think I should send it in to get tuned again or switch to a different ecu? I never actually looked for an ecu for the fbody wonder how much they are. But yes it is located under hood on passenger side against firewall
 

Chuck Leeper

Toxic old bastard
Staff member
Before throwing more parts at it, data log it. This is about the best way to narrow down the issue.
Any check engine lights?
Being that the issue is at a specific rpm, it could well be that one of the sensors that output voltage, depending on the rpm/load, is faulty.
IE: TPS, MAP, MAF.
Pull the ecm, and take a look at the connectors, pins, and see if the case is showing signs of being wet.
Do the log from a cold start. Hook up, key on, record for a few seconds, start. Log it til it warms up. Run the rpms up to the 2500 point, and see if the issue shows up. Save the log.
Do another log while driving.
We use HP Tuners and EFI Live for such.
 

84turbo6

Member
Yes the check engine light is on but it's for no rear 02's and egr delete, guess I should mention the mods, not very many long tubes no cats, Lid, egr delete and upgraded cooling. Alright if the weather is good today I'll start checking out the ECU, man do I miss my scanmaster 2.0
 

84turbo6

Member
Okay soo new development. Car will not start when it is raining, or even humid out, as soon as it dries it starts right up
 
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